This invention relates to a cap for closing the burner of a fuel cell for protecting the upraised tabs of the burner wick and, in particular, of a cap containing an impression die that is arranged to shape tabs of a predetermined configuration when the cap is closed over the burner.
In U.S. Pat. No. 5,211,553, there is described a liquid fuel cell that includes a burner having a divided wick. The wick contains two upraised tabs that can be angularly separated to control the heat output of the fuel cell. Placing the two tabs in face-to-face contact provides for low heat and maximum burning time. On the other hand, extending the length of and angularly displacing the tabs by up to 180.degree. produces high heat and minimum burning time. Most users, however, find that a "standard heat" setting somewhere between the two extreme positions is best suited for their average needs as for example, when warming a chafing dish or the like.
Most fuel cells equipped with adjustable wick tabs are simply put into service without regard to the tab setting which can be "as received" from the factory or in a setting selected by a prior user. This, in turn, generally produces unsatisfactory overheating or underheating. Those users attempting to properly adjust a split wick to a standard or normal setting oftentimes become frustrated in their efforts because of the infinite number of settings available between the two extreme wick settings. Failure to locate the standard heat setting again, results in ineffective fuel cell performance and user dissatisfaction.
As explained in greater detail in the above noted '553 patent, and in U.S. Pat. No. 4,526,530, it is important that the burner employed in this type of fuel cell be properly vented. A primary vent passage is typically arranged so that in addition to venting, it also collects and returns excess fuel from an over saturated wick back to the fuel cell reservoir. A secondary venting system is designed to operate as a stand pipe in the assembly, to relieve the pressure in the reservoir in the event the primary vent passage becomes flooded with liquid fuel. Under the combined venting action of the secondary system and the slight head pressure built up by liquid fuel collected about the primary vent, the surface tension built up about the primary vent openings is overcome, enabling the collected fuel to drain into the reservoir. Once the passage starts to drain, it will normally continue to drain until all of the fuel is completely removed from the passage. It has been found that on occasion the wicking material can become tightly packed within the burner thereby closing the burners' secondary vent channel. This may result in ineffective warming and in extreme cases, burner failure. As will be explained below, the apparatus of the present invention is designed to insure that the burner is properly vented at all times.